People with Diabetes Mellitus (DM) and peripheral neuropathy are at high risk for skin breakdown and subsequent lower extremity amputation due to unnoticed, repeated trauma (plantar pressures) to the plantar foot during walking. Current rehabilitation methods use subjective methods to fabricate orthotics to reduce plantar pressures, but ulcer recurrence is high (30-57 percent). The long term goal of this project is to reduce the incidence of skin breakdown and subsequent amputation by objective orthotic fabrication based on the internal structure of the foot. We have developed methods of visualizing and measuring foot structure from spiral x-ray computed tomography (SXCT) data in conjunction with plantar pressure measurements. The purpose of this proposal is to combine SXCT imaging methods and plantar pressure analysis to quantify the relationship between internal structures and external pressure on the foot to improve orthotic design. We will achieve this purpose through the following specific aims; Aim 1: Validate SXCT volumetric imaging methods for accurate and reliable morphometric assessment of bones and soft tissues in the foot. Aim 2: Measure structural changes which occur in the foot as a result of the complications of diabetes and peripheral neuropathy, and determine how these changes are related to plantar pressures during loading. Aim 3: Generate and validate 2D planar and 3D mathematical solid models of the foot from SXCT volumetric data. Determining the differences between the Diabetic and healthy foot, and how these differences relate to plantar pressures will help to understand and manage the structural factors that contribute to skin breakdown. Creation of the mathematical model will enable us to visualize and manipulate the internal and external 3D structure of the foot in a computer aided design environment from SXCT measurements and may have immediate implications for orthotic design. In future work, we will use this mathematical model and computational mechanical analysis to optimize orthotic design. The predicted optimal orthotic design for a given foot structure can then be manufactured and evaluated in a clinical trial during later phases of the research.